RFR: 8314850: SharedRuntime::handle_wrong_method() gets called too often when resolving Continuation.enter

[Oli Gillespie]

On Wed, 23 Aug 2023 14:25:12 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

> Please review the following fix. The check in SharedRuntime::reresolve_call_site() "caller.is_compiled_frame() && !caller.is_deoptimized_frame()" fails when caller is Continuation.enterSpecial because it is a native method. This means that if the static callsite to Continuation.enter was patched to point to an nmethod and then the nmethod was marked non-entrant we will always call SharedRuntime::handle_wrong_method() thereafter when resolving Continuation.enter because the callsite will never be reset back to the clean state. Thanks to @kuksenko for all the performance analysis while debugging this.
> I tested the patch by running the test included in the original report (loom-dev mailing list) and verifying the issue is fixed. I also run mach5 tiers1-3 for sanity testing and will run all the upper tiers too.
> 
> Thanks,
> Patricio

Thanks! Indeed lowering `jdk.virtualThreadScheduler.parallelism` helps a lot and the improvement of the patch compared to before is quite clear at lower values. I'll be sure to test out the patch in my real workloads later.

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PR Comment: https://git.openjdk.org/jdk/pull/15403#issuecomment-1690149138